Trials to improve the response of Orechromis niloticus to Aeromonas hydrophila vaccine using immunostimulants (garlic, Echinacea) and probiotics (Organic GreenTM and Vet-YeastTM)

Abstract

This workaimedto investigatethe roleof some immunostimulants and probiotics in improving the response of overwintered tilapia to Aeromonashydrophila vaccine. In thisstudy,15000 Nile tilapia fry(Orechromis niloticus)were collected and divided into five groups. Group 1 wasthe control, groups 2 to 5 were fed diet supplemented withgarlic, Echinacea, Organic GreenTMand Vet-YeastTMrespectively for 5 months. Vaccination with A. hydrophila bacteriawas done by the end of the feeding experiment. The antibody titer of the vaccinated overwintered tilapia of all groups showed no significant changes during the same sampling time. A significant high valuein the antibody titer was recognizedin vaccinated overwintered tilapia at the end of 6th-8thweek post-vaccination(PV) in the control group and between the 4th–8thweek PV in the immunostimulant supplemented groups (Groups 2-3), and between the 2nd–10thweek PV in probiotic supplemented groups (Groups 4and 5). The challenge infection of the vaccinated tilapia showed the highest mortality in Group1 while the lowest mortality was seen in Group5. However, maximum protection after challenge was seen at 6thweek PV in othertreated groups. The immunostimulants and probiotics under test proved efficient inimprovingthe immune response to vaccination whichwill improve the resistance of tilapia fry against infection during the winter. The overall results are promising to implement overwintering fry culture program to economically maximize and efficiently use the available aquaculture facilities throughout the year.